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benonemusic writes "The commercially available D-Wave computer has demonstrated its ability to perform increasingly complex tasks. But is it a real quantum computer? A new round of research continues the debate over how much its calculations owe to exotic quantum-physics phenomena. 'One side argues there is too much noise in the D-Wave system, which prevents consistent entanglement. But in an adiabatic device, certain types of entanglement are not as vital as they are in the traditional model of a quantum computer. Some researchers are attempting to solve this conundrum by proving the presence or absence of entanglement. If they show entanglement is absent, that would be the end of the discussion. On the other hand, even if some of D-Wave's qubits are entangled, this doesn't mean the device is taking advantage of it. Another way to prove D-Wave's quantumness would be to confirm it is indeed performing quantum, and not classical, annealing. Lidar has published work to this effect, but that triggered opposition, and then a counter-point. The debate continues.'"

Measure correlations between the two systems. If you have entangled, oppositely polarized photons and you simultaneously pass them through aligned polarizers then one will always pass through the filter and one will always fail. It is impossible to recreate this in any classical system without communication between the photons.

If you can perform the same type of measurement with entangled qbits in a manner where it is physically impossible for them to communicate (e.g. make the two measurements simultaneously) you can confirm their quantum nature.

Good question but I simply don't know enough about the D-wave to be able to answer. My point was just that it is possible, in principle, to devise such a measurement but how to do that in practice will depend heavily on the details of the D-wave.

You can do what Alain Aspect did which was to show that statistically a system can show the repeatable statistical measurements (using Bell's Theorem) that indicate that entanglement is happening. Then let the system/computer do it's thing with some confidence that entanglement is in play.

Simple. Make it do something only a quantumly entangled system could do in a given time period like reverse factorization or whatever. So far, they haven't done that. Their excuse is a lack of sufficient quantities of qubits to determine a speed change in factorization. Basically a normal CPU or ASIC could have solved the equation they demonstrated in 1 ms but a quantum one could solve it in a billionth of a millisecond but you can't measure that small of a time frame so you have to take their word on i

Can someone explain to me how this chip could be calculating anything unless the quantum part was working?

Isn't it like a car that has an electric motor or a gas one, but not both? How can they be confused which engine is running? Who builds a backup normal processor then what, it fills in if the quantum one doesn't work right, and they have no way to tell if this backup kicked in?

Can someone explain to me how this chip could be calculating anything unless the quantum part was working?

D-wave is very secretive about how their machine operates and do not respond to academics who want to know exactly how it works -- this is the source of much of the speculation. On top of that you need to specially code your instructions for it, because it can only do a subset of what a general quantum computer could in theory do.

One of the earlier papers that supported their claim of actual quantum annealing is linked and discussed at this blog post [wavewatching.net].

D-Wave's publication list [dwavesys.com] is too long at this point in order to give a synopsis here, but there are many blogs that follow this story, so it really isn't that hard to get a more up-to-date picture.

The D-Wave engine can indeed solve some specific optimisation problems by a method called adiabatic annealing. Essentially this done by encoding the problem to be solved in some initial state of the physical components of the engine, and letting it evolve without exchanging energy with the outside world (this is what adiabatic means). The evolution is done in such a way that the solution to the optimisation problem eventually appears (this is the annealing part) with some probability.

The engine definitely works, this is not disputed. However there is some debate whether the way the engine works is essentially classical or essentially quantum. At the moment the engine is not especially powerful and it is very noisy, so there is no easy way to tell. In the 3 papers cited in the Fine Article, one says this is definitely quantum because the way the system evolves does not match the way classical annealing is simulated (simulated annealing (SA) is a very popular way to solve some complex classical optimisation problems). The second paper says that it is still possible to achieve the signature observed in the first paper by purely classical means, so this is not so clear. The third papers says that this is correct, but that there is more to the signature than was reported in the first paper, and that *this* is more likely to be quantum than not.

Feel free to contradict me. At any rate, and this is not disputed, the D-Wave engine does not work in the way quantum computers are expected to work in the literature about this topic. It would not be useful to solve factorisation problems as in the Shor algorithm [wikipedia.org]. Rather, it would be useful to solve some optimisation problems in a faster way than with classical or traditional CPUs or GPU. This is still very useful, although at the moment the D-Wave computer's inner working are mostly secret, not hugely fast, and noisy. So D-Wave's qbits are a bit of a misnomer. They should be called something different so as not to engender confusion, perhaps obits (optimisation bits)?

Yeah... I watched a talk by a D-Wave guy. This is a summary of his talk: "So, you have an NP-Complete problem. We have a quantum solver that works on a large graph with a special structure. If you can find a homomorphism from your problem into our graph structure, and you can figure out how slowly to evolve the adiabatic process, then we can solve your problem!"

Okay, that's great. But finding that graph homomorphism? Probably NP-Complete itself. Figuring out how slowly to evolve the system? I have

Theoretical Quantum computer using entanglement to perform their calculations make no claim to solve NP-hard problems. They can only solve some very specific class of problems, that are well identified but are still interesting. Integer factorisation is one of them, but factorisation is not thought to be in NP-complete [wikipedia.org], although we are not certain at this stage.

There is an old article in PNAS that says that adiabatic quantum computers are theoretically no better [pnas.org] than classical computers at solving NP-hard problems. So even if D-Wave had a truly working adiabatic quantum computer, it is not clear that it would perform orders of magnitudes better than what we have now.

Anyway all of this is very interesting to watch, but the fact that D-Wave is so secretive is not very compatible with progress in the field.

No, the D-Wave machine can only solve the Ising equation. Universal adiabatic quantum computers have been shown to be able to emulate gate model quantum algorithm, but for the more restricted current D-Wave architecture a mapping is (probably) not possible. Nevertheless the class of problems they can solve is still pretty large, and is applicable to useful optimization use cases and learning algorithms.

Ordinarily, you would look at the computing power. If it is significantly larger than conventional physics can explain, it must use quantum effects. Unfortunately, this "magic black box" is in no way faster than traditional computers, just a lot more expensive, hence the hand-weaving.

My money is on this being pure fraud. Would not even surprise me if there is a conventional computer hidden in there somewhere that does the calculations.

I'm personally reasonably convinced that D-Wave's engine is novel and does offer some new ways of performing various specific calculations. The literature about it exists and is quite interesting for people interested in optimisation. However I'm not sold to the technology yet, essentially classical CPUs can perform the same type of calculation that D-Wave's computer can at the moment, at a much lower cost. This might change in the future though.

That'll be a lot of effort for a fraud, especially since you then have to fake all the qubit specific data that goes into the publications. And the chip samples they have on display very much looks like Josephson junctions circuits and nothing like regular chips. (And the integration density they have for this process could not at all deliver reasonable classical performance).

And do you realize that Josephson circuits are especially fast and well understood, if not cost-effective? And that in addition there does not need to be any resemblance between what they display publicly and what is actually in the machine? And that what is actually in the machine does not need to be created with the same process or by them at all? Until somebody competent in detection technological fraud disassembles one of these, we do not know. I bet disassembly voids the warranty or even destroys the t

The contraptions Rossi builds are cheap and look like a plumber put them together. On the other hand D-Wave has chips samples on display that are produced by a special purpose foundry that can produce Niobium SC circuitry. That took some serious investments.

Rossi supposedly sold his house to finance his venture, D-Wave is backed by the likes of Steve Jurvetson and Jeff Bezos. Ross

Hasn't the benchmarks already placed it above pretty much any computer in the tasks it can do within its full size?

Mind you, I guess even if that were true, if it wasn't quantum entanglement taking place, it would still be pretty big because they still managed to find a way to make a non-quantum computer way ahead of the competition.

If it is a quantum processor, it would be similar to say... the math co-processor, still baby steps towards a full, integrated circuit.They even say themselves that it is only u

Last state of my knowledge is it is slower than a traditional computer in a fair comparison. There are some benchmarks though that have a traditional computer simulate this thing, and, not surprisingly, the simulation is slower than the real thing. That is about the most unfair comparison possible though.

Hasn't the benchmarks already placed it above pretty much any computer in the tasks it can do within its full size?

My understanding was that the benchmarks - at least the one that was quoted as showing a "3600x speedup" - weren't even comparing the same thing: the D-Wave computer was running the quantum adiabatic annealing method, which is the only way it can be programmed, while the conventional CPU was running an exact solver. The latter is expected to be vastly less efficient (but more precise). When a group of computer scientists came up with an annealing method to solve the same problem on a conventional CPU, they ended up with something just as fast as the D-Wave system.

The benchmark did indeed not demonstrate a quantum speed-up, but it in fairness to D-Wave this was a test designed based on the customers requirements i.e. for them acing this benchmark was good enough to justify investing in this technology.

My understanding is that the algorithm that was comparatively fast on a classical computer was hand optimized by a graduate student, it was not a generic annealing algorithm solver.

But the paper on this effort of 'beating' D-Wave on a classical machine is yet to be published, so this is all from blog hearsay.

Could you elaborate a bit on this? I had the impression that D-Wave's users had to map their problem to fit what D-Wave computes, not the other way around. That would make comparisons with a specialized software solver appropriate, wouldn't it?

The blog post in question [archduke.org] also includes a link to the source code [github.com] of the specialized solver (Prog-QAP), and others have confirmed that it produces the same results as CPLEX, the general solver that D-Wave beat.

CPLEX is indeed slower than D-Wave, though newer versions have brought the factor down from 3600x to 14x [ibm.com]. But again, CPLEX is a general solver, while D-wave is specialized hardware. The specialized software solver Prog-QAP is *much* faster than CPLEX, and gets a 12000x speedup over D-Wave when running on a single core.

But all of that is a bit old, and it may be that D-Wave has produced more impressive results after that. I hope D-Wave's approach results in something able to beat classical computers, even if it doesn't lead to a general quantum computer. But I really dislike all the secrecy they employed - that is not how science is supposed to work. The fraud speculations they have had to endure are entierly self-inflicted due to this secrecy.

I was referring to the paper by Mathias Troyer et. al. that is yet to be published not the effort that Alex Selby writes about (thanks for the link).

Will have to read the latter in more detail to get a good grasp of how much effort is required to beat the benchmark with Alex's approach. Two caveats: On first glance I am not sure if he has the same training data (he mentions he communicated with Cathy McGeoch) - if he does it'll be interesting to see how stable his generic approach is when the problem domai

properly understood, Quantum Entanglement is at the core of all Quantum Physics [wikipedia.org]

No it is not. It is one of the features of quantum physics which is the hardest to understand and, arguably, we still do not have a good grip on it. However that by no means puts it at the core of all quantum physics: there is far more to QM than quantum entanglement e.g. tunnelling, self interference etc.

Yes, but do you understand it? There is a huge difference between being a "feature of QM" (as your source accurately states) and being "at the core of QM" as you incorrectly state. Entanglement is a feature of QM but there are many other features of QM that have nothing to do with entanglement.

properly understood, Quantum Entanglement is at the core of all Quantum Physics

To a US English speaker, this phrase can generally be translated to mean "All quantum mechanical reasoning relies on quantum entanglement" which is false. But the phrase you state leaves room for interpretation and can certainly mean "quantum entanglement is one of the basic features of quantum mechanics" or even "quantum mechanics requires quantum entanglement to be true". It's just that the standard way the phrase is parsed

I did not misquote you: a fundamental feature is just one that derives from the fundamental nature of quantum mechanics. That does not mean that it is central to the nature of quantum mechanics. To use an example from my own field of particle physics I could correctly say that kaon oscillations are a fundamental feature of particle physics but it would be ludicrous to say that this are "at the core" of particle physics.

So you might want to take a deep breath and calm down a little. Trying to claim that t

I think you will find that it's the other way around...or do you really have trouble comprehending the spoken word and pictures to give but two examples. Sorry but it is clear from this that you do not understand what 'fundamental' actually means so your confusion with quantum physics, which is tricky at the best of times, is understandable.

No, if I am being pedantic it is about the science. "Fundamental feature" and "at the core" do not mean exactly the same thing in a physics context. One means a behaviour that occurs under certain circumstances and the other means central to the explanation of the physical laws. For example the electron-positron annihilation a (fundamental) feature of QED but the fermion-photon vertex is at the core of QED. The first is a result of QED that occurs under the right circumstances the latter is something that

It's not often I get to see such a well reasoned, evidence based scientific argument. Might I suggest you publish this in a journal? The scientific world clearly needs to see the article "You are perturbed I am ****right****" by G. Justin (I hope you don't mind the addition of asterisks but I think that really adds a little more credibility and you do use them to such good effect almost everywhere else).

the EPR Paradox was a criticism of a **factual inaccuracy** which was proven right via the sources cited...

I also apologize for clearly completely misunderstanding the EPR paradox. I, like the rest of the scien

No the problem is that you believe that you are correct and nothing and nobody will persuade you that you are wrong. In your previous post you literally said so. You keep coming back to the same argument again and again which basically boils down to "I am right and you are wrong". Anyone who is older than 5 and not mentally unbalanced should not need to be told that this is massively unconvincing because, whether you can conceive of it or not, there is always the chance that you might be wrong.

I expect journals or widely accepted books...copy/paste of the wikipedia (including the sources on the wiki of course) will do just fine

I won't respond if you just post links to arvix...you have to go aaaaalllll the way back and identify where we disagree on the EPR Paradox and **how** your evidence counters what I've shown (the einstien/shrodinger info)

I'll accept the same stuff I have used...you quote a wiki with proper sources and I'll go to the wiki and check the sources..

No, you offered one link to Wikipedia where there was a comment mentioning that the EPR paradox is a feature of QM. You then completely misinterpret that and come to the conclusion that it is at the core of QM which means that it is related to the explanation of al quantum phenomena. Worse you seem to think that Wikipedia is a better reference source than arXiv. This would be laughable if it were not so sad.

As for me providing evidence you are the one making the claim so the onus is on you to prove what

Sorry - I did not realize that you did not possess any QM text book. If you are going to comment on QM you really ought to get one and read it - you might learn something. If the problem is that I dared to suggest a textbook as a reference instead of Wikipedia then you really ought to think things through a little deeper. I can easily write, or edit, a Wikipedia article to support my point of view, post a link to it. If you really want me to go to that trouble I suppose I could but honestly a text book is a

put yourself in the other situation...what if *you* made a claim, with evidence (the wiki i linked to used Einstein as a source for the claim quoted...i have never just linked to a wiki and called it good...it's the **sources the wiki uses**)

would you just change your mind b/c some random/.'er said "no, you are wrong"

You'd want evidence of some sort for something as complex as QM...not just some guys damn word...

Umm...try reading that link again because that is completely wrong. The claim that it is a feature of QM came from the wiki page and has all the authority of the random internet person who wrote it. The paper which is cited on that page was written by Einstein as a way to convince people that QM was wrong. Einstein himself never believed in QM and applied the laws of QM to the entangled two photon system to try and show that this was a crazy feature of QM and so QM had to be wrong. It was later experimenta

just make sure to note the **page number** of course...and I still need you to **identify where your and my ideas of the EPR Paradox diverge...**

Explained above. Since there is no need to use entanglement to explain phenomena like electron orbitals (which is my point) there is no page number where it says "we do not use entanglement here because it is a feature of QM" just like they don't say "we do not use the infinite square well potential here". There are lots of things they don't use and it would be a VERY long chapter if they stated each and every one. So you have to read through and understand the chapter to see that there are phenomena which

It does but you have to read through and understand a quantum phenomenon in order to know that you can explain it without any reference to entanglement. Here's a fun fact, I checked and I do actually have the second edition (although certainly an earlier reprinting) and if you go to page 421 it describes the EPR paradox as a theoretical exercise which attempted to prove the realist position. Happy? Of course if you had actually read Einstein's paper directly (the one you keep indirectly citing) you would h

...because I thought you were intelligent enough to (a) read and understand your own references and (b) follow simple arguments and do a little looking up on your own without having to be told precise page numbers in specific books. My mistake, I know better now.

I don't want to hear any shit about 'at the core' vs 'fundamental' b/c that shit...

That is what we were talking about. It's what I commented on and what you replied to!

1. we did have a direct clash on ideas, 2. you knew you were wrong and tried to use rhetoric to "win", 3. I forced you to actually engage the topic, and 4. have proven you wrong

Wow - just wow. This whole discussion was your claim that "Quantum Entanglement is at the core of all Quantum Physics" which is just plain wrong. You've tried to claim that this was just semantics, then claimed that your references supported this (when they did not), then demanded detailed references and finally when everything failed as a last act of desperation you are now trying to claim that the discussion was about something else.

you are wrong...true non-local, quantum teleportation exists...as you admit

Errr...what? I say true non-local, quantum teleportation exists and the

see, if your assertation is right, and I'm wrong, then the research team in TFA can be said to be doing 'true quantum computing' w/o having entanglement be involved at all...no non-locality, no quant. teleportation...but, according to you, still 'quantum'

you are wrong...true non-local, quantum teleportation exists...as you admit ("check the journals")

the research group in TFA is *not* doing Quantum Computing, b/c to do true Quantum Computing current understandings of 'entanglement' must be involved in the s

I responded to a specific claim in your post which I quoted and you replied in kind to that. Only in the last few posts have you suddenly decided that we were discussing something else. This is not normal, rational behaviour.

So in one sentence you say that I did not respond to a specific claim and then in the next sentence you say that I did since the selection I responded to contained a specific claim? I'm not trying to avoid a debate there simply isn't one going on because I can neither agree nor disagree with you since your statements are not logically consistent. Worse, having finally resolved what we were talking about you somehow can't accept that and are now inventing something else. At the risk of repeating myself this

Was the claim I quoted and showed was wrong "Quantum Entanglement is at the core of all Quantum Physics"? Are you capable of conceiving that someone can respond to a claim in a post which is related to the topic being discussed?

Quantum computers by their very nature employ quantum physics so I'm at a loss to see how a discussion on the nature of quantum physics can be considered "off-topic". I'm sorry but, other than curiosity to see how far Slashdot can nest comments, I really don't see that there is much point in continuing this.

Any sensible discussion requires two rational people. However it appears that having conceded the claim on quantum physics you are now determined to believe that we were having a conversation about so

There should be plenty of problems a quantum computer could solve in polynomial time that would take classic computers eons to solve. Start solving those problems and it's a quantum computer. Simple as that.

Exactly, it doesn't really matter if it is a real quantum computer or not, only that it can complete certain computations that people need much faster than a traditional computer. If it solves that problem for someone then the rest of the debate is academic.

Exactly, it doesn't really matter if it is a real quantum computer or not, only that it can complete certain computations that people need much faster than a traditional computer. If it solves that problem for someone then the rest of the debate is academic.

Wait, it does matter whether this is a quantum computer or not. If it *is* a quantum computer then the calculations can be trusted to be accurate and precise based on the fundemental principles driving the solutions. If it is *not* a quantum computer all the results from the machine may be so horribly wrong that they cause serious accidents, damage or loss of life. The problem as stated above in the comments is that some of the calculations take so egregiously long ("eons") on traditional computation devic

That's not how quantum computers work or how they are used. You don't get a definite answer, just a highly probable one. You then have to verify it with a normal computer. The problem that the quantum computer solves is that a normal computer has to try every verifying possible answer until it finds the right one. Each test may only take fractions of a second, but you have to do so many of them it takes an unreasonable amount of time.

Consider the hypothesis that the DWave machine is a superposition of classical and quantum computing. By some observations it is classical, by others quantum. As some point a measurement will be preformed on the machine, and it's state will resolve into either a classical physics computing device or a quantum physics computing device.

This situation is completely reasonable give the current state of the art in quantum computing.

Making accusations of "marketing hype" and unethical behavior are irrelevant. Whatever it's doing, it's not digital computing. Even if it turns out to be classical physics, it is still advancing the state of the art in non-digital computing.

No matter how DWave does in the future, quantum computing is still going to happen in the near term. Dwave is not going to change that under any circumstances.

Getting bent out of shape over this is a waste of effort. Even the experts are not in agreement. This is how progress occurs at the cutting edge.

No way I'm gonna try one of these until they get the bugs out. Instead of a blue screen, I'll get a black hole and those Higgs bosons all over the carpet. My wife will kill me. Plus, they probably cost like over a thousand bucks.

But I bet GTA V runs like a banshee on it. No screen tearing, but possibly tearing in the fabric of space and time. As soon as Tiger Direct starts selling them, I'm in for one, but you best believe I'm gonna be wearing my lead codpiece when I sit in front of that thing.

Because *IF* it can be developed, someone will eventually develop it, and probably sooner rather than later. Technological advances depend less on creative genius and more on previous technological advances. It's like how radar was developed simultaneously by about a half-dozen different nations, but they were all trying to keep this supposed strategic advantage secret from one another. It's not that it was a coincidence, but rather that the time was right, and the pieces were all in place.

Isn't it better to develop a quantum computer first, so that you know to stop using vulnerable forms of cryptography? Anything else is just sticking your head in the sand. Failing to develop it yourself will not stop the other guy from doing it.

I wouldn't be surprised if there already is, somewhere. The NSA is certainly reading every journal in the field, looking out for the elusive breakthrough. If they saw one being made they would likely surpress it for a few years, so they could take advantage of that window of opportunity before someone else invented it or at the very least have time to quantum-proof the US military and diplomatic communications before the tech went public. Their counterparts in other co

The problem is mostly on the engineering side, it'll be hard to build up industrial capabilities of the scope needed for a useful universal gate based QC and conceal if from the rest of the world. It's not like coming up with a code cracking algorithm, the latter could be kept classified quite easily.

"This ability would allow a quantum computer to decrypt many of the cryptographic systems in use today."

Nobody sane, no, but the NSA and GCHQ would love that. While lighting a cigar under the "no smoking next to the nuclear weapons" sign in the pool of suspicious green ooze at the abandoned military experiment base codenamed Icarus 13 that was formerly the Lovecraft House for Angry Psychic Orphans built on top of a desecrated Indian burial ground.

Sorry to blow your bubble, but you can actually look at the chip that's inside D-Wave's boxes. It doesn't have transistors, it has Josephson junctions. Tell me how you can get any calculations out of those unless you do physical annealing with them.